#include <iostream>
#include <cmath>
using namespace std;

const double PI = 3.1415927;

double scircle(double radius) {
    return PI * radius * radius;
}


double srhombus(double len, double theta) {
    return len * len * sin(PI * theta / 180);
}

int main() {
    double r = 12.5;
    cout << "circle radius = " << r << "  erea = " << scircle(r) << endl;
    double a = 21.4, theta = 45;
    cout << "rhombus length = " << a << "  erea = " << srhombus(a, theta) << endl;

    return 0;
}
